Letter of marque

Letters of Marque were warrants/commissions used as a means of employing people (usually pirates) as privateers during times of war. Privateers were essentially pirates flying the banner of a patron country, and they were commissioned to sink the ships of the country's enemies, with Royal Navy privateers from Great Britain being employed to sink Spain and France's ships during the War of the Spanish Succession. However, privateers usually returned to piracy when the wars ended, as there would be no need for them in times of peace.